Virtual Journal of Laser

InGaAsP–InP square microlasers with a vertex output waveguide are fabricated by planar processes, and the etched sidewalls of the lasers are confined by insulating layer
$hbox{SiO}_{2}$ and
$p$ -electrode Ti–Au metals. For a square microlaser with a side length of 30
$muhbox{m}$ and a 2-
$muhbox{m}$ -wide output waveguide, a continuous-wave threshold current is 26 mA at room temperature and output power is 0.72 mW at 86 mA. The mode interval of 21 and 7.4 nm is observed for the microlasers with the side length of 10 and 30
$muhbox{m}$ , respectively. Finite-difference time-domain (FDTD) simulations indicate that the lasing modes have incident angles of about 45
$^{circ}$ at the boundaries of the resonator.

A two-step roughening process that uses a KrF excimer laser and KOH chemical etching for the n-GaN layer surface of vertically structured GaN-based light-emitting diodes (VLEDs) to yield circular protrusions with hexagonal cones atop for light extraction enhancement is demonstrated. A possible mechanism of the formation of the circular protrusions commenced by laser irradiation with nonuniform etching rates at sites with various dislocation densities was investigated. An improvement in light output power of about 95% at 350–750 mA compared to that of flat VLEDs was obtained for the two-step roughened VLEDs, which is attributed to the increase in surface emission area and dimensions of roughness, and, in particular, the decrease in the n-GaN layer thickness.

We propose and demonstrate a heterogeneous optical access network using wavelength-splitting at remote-node to mitigate the Rayleigh backscattering (RB) noises. Two continuous-wave carriers are generated from each laser for wired and wireless applications, respectively. Results show that the scheme can effectively mitigate RB noises.

In coherent optical long-haul transmission systems, orthogonal frequency-division multiplexing represents a promising modulation format. However, due to long symbol length, laser phase noise can be a major impairment. In this manuscript, the RF-pilot-based phase noise compensation scheme is analyzed and compared to conventional common-phase error compensation. It has been shown that the RF-pilot-based phase noise compensation scheme allows for a considerable increase in tolerable laser linewidth as compared to conventional common-phase error compensation at the cost of an increase in system complexity. For a 112-Gb/s transmission scheme, the tolerable linewidth is increased by a factor of ten as compared to common-phase error compensation.